JSFiddle - React, Tailwind, and code Playground

HTML

<div class="main"> <a class="blah">blah</a>

</div>
<div class="main"> <a class "blah">blah</a>

</div>
<div class="main reply"> <a class="blah">blah</a>

</div>
<div class="main reply"> <a class="blah">blah</a>

</div>
<div class="main reply"> <a class="blah">blah</a>

</div>
<div class="main"> <a class="blah">blah</a>

</div>
<div class="main reply"> <a class="blah">blah</a>

</div>

JavaScript

$('.blah').on('click', function () {
    var new_add = '<div class="new">xxx</div>';
    $(this).parents('div.main').siblings('.main:last').append(new_add);
});